Bathroom switch - via relay?

Hi,

Currently, my bathroom has a fan which switches along with the light and stays on on a timer afterwards. Most of the time, this is unnecessary - if I fill up a glass of water before going to bed I don't need a fan waking up everyone else in the house.

As part of my bathroom refit, I'm planning to disconnect the fan totally from the lighting, and instead switch it via a flow switch on the shower supply. I also want a manual button strategically positioned next to the toilet flush :-). This would be a momentary switch so that the fan starts and then runs-on on the timer.

My question is how to handle the wiring of this switch. I currently have a nice brushed-steel button that would look the part. It happens to be rated to 250v/5a, but AFAIK is not IP-rated. I also have a relay that will switch a mains supply from a 6-12v signal current. One approach would be to have the relay in a suitable enclosure in the roof space above the bathroom, with the button controlling the low-voltage side from below. This keeps mains out of the bathroom, but is it acceptable from a regs point of view? I'm confident that I can built it safely, but these aren't quite the same thing :-)

Alternatively, I could buy an IP-66 button (eg MP0031,

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) and wire it directly. Would this be OK? The back of the button would be inside a substantial piece of boxing-in, effectively a stud wall. This would have access points in it, but not routinely openable (ie require cutting sealant).

Cheers,

Pete

Reply to
Pete Verdon
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What about a flow switch on the toilet cistern supply?

I'm also picturing a momentary action pullcord switch with the end tied around the flush handle, and you could always operate it early should something rather iffy happen;-) Probably all rather too Heath-Robinson, but a plain momentary action pullcord switch remains a possibility (they usually come with a long red pullcord, as they're used for alarm callers).

Reply to
Andrew Gabriel

Andrew Gabriel coughed up some electrons that declared:

And the shower/bath cold feed. Now that *is* a good idea!

Reply to
Tim S

Provided you use a suitable mains transformer to supply the low volts, then yes. I have a similar idea to add in the shaving/makeup lights round the mirror which aren't always needed. And I dislike pull cord switches.

Reply to
Dave Plowman (News)

That's no good - I don't want the fan coming on when someone goes for a pee at night. The switch next to the toilet is to be a manual one, with a fan symbol etched on it.

That's what I am doing. I don't want steam blowing around the room causing mould, so whenever the shower is turned on so will be the fan.

Pete

Reply to
Pete Verdon

...and look horrible :-)

I don't really want a pullcord for the main light either, though I might have to settle for it. The continental habit of putting light switches outside the room I find annoying, and IP-rated switches tend to be designed for outside and would look wierd in a bathroom.

Pete

Reply to
Pete Verdon

I went for 2 pull cords. One (with a shorter string) controls the shower light and the fan, the other controls the rest of the lights. This system has been in use now in both bathrooms for several years and has been very successful.

Dave Dave

Reply to
NoSpam

Perhaps a motion detector would help

;-)

Reply to
Frank Erskine

I'm actually planning to use a PP3 battery. I know it sounds a bit odd, but since it would only be energising the relay for a few seconds per day it should last for ages, and it will be in my boarded-out loft where I can easily change it when the time comes. All the transformers I looked at drew a few watts of power even with no load - I'm far from a tree hugger but knowing that something is sitting there taking power while doing nothing would annoy me.

That's good to hear. Mind elaborating slightly on "how you know"? Is it a common practice, or specifically mentioned in regs, or similar? I wouldn't want to go trusting everything I read on the Internet now, would I? :-)

Cheers,

Pete

Reply to
Pete Verdon

Groan :-)

Pete

Reply to
Pete Verdon

Pete Verdon coughed up some electrons that declared:

Hmm - good point. What we need is the "smelly bastard" sensor...

Reply to
Tim S

I actually briefly flirted with the idea of putting something like

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on the switch instead of a fan symbol :-)

I thought the joke might not last.

Pete

Reply to
Pete Verdon

To be honest I've had great success with these :

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(A 3 AA battery operated PIR & Photocell controlled LED Nightlight)

No clicking of lightswitches in the middle of the night, great if you have elderly relatives staying who have to visit the bathroom frequently and don't know where the lightswitches are. Battery operated so not constrained by the need for a mains supply. The 3 AA batteries seem to last us about 6months. Plenty enough light to light a whole bathroom, landing or staircase to complete the "intended function". ;-)

Only disadvantage I've found is that if you have them in the bedroom in such a position that they can "see" head end of the bed, then they come on everytime you scratch your nose during the night. However this is easily avoided.

Derek

Reply to
Derek Geldard

Simplest way would be with a timber fan such as you already have - however disconnected from the light switch. Plus an additional external humidistat. That way you can trigger it either from the push button (which will cause it to run for the timer duration) or from the humidistat which will cause it to run until the RH falls below threshold + an extra timer duration.

The main problem with a push button of inappropriate rating for the location will be what effect the ingress of moisture will have on the switch - regardless of any voltage exposure risk.

A momentary action pull switch may be better for the manual activation.

You can get momentary action rocker switches as well that look like ordinary electrical accessories. These may prove somewhat more maintainable.

Reply to
John Rumm

You can use an ordinary light switch in a bathroom as long as its outside zone 2 and is not going to get exposed to unreasonable levels of moisture.

Reply to
John Rumm

In my case the transformer is only powered up when the lights are on. However, I'd not fancy using a PP3 and a standard relay - it won't last long. You need a specialised motorised type which needs no holding current. Like the type used on battery programmable thermostats etc.

The regs don't cover every eventuality word for word, but operating mains via an ultra low voltage relay is standard practice where safety matters.

Reply to
Dave Plowman (News)

I am tempted to put a level sensor in the cistern, so it is activated only when the toilet is full flushed, not the short flush!

Toby...

Reply to
Toby

No - in mine the primary side of the transformer would be on all the time, and the battery is only used (and relay energised) while the button is depressed. The idea is that pressing the button looks to the fan like someone flicked the light on and off, and it then runs for the duration of its timer.

Thanks. I was just concerned that this might be outlawed on the grounds that a stray wire in the relay box could make the ultra-low-voltage side live. Though the fact that the switch is actually mains-rated in this case means you'd still need a second fault (or a lot of water) to get a shock.

Pete

Reply to
Pete Verdon

So I see - zones are a relatively recent thing, aren't they? Seems very weird to be able to put a normal switch in the room :-)

The switch would be at the other end of the room from the shower, but might possibly be within 0.6m of the basin. However, I'm not sure even then - I might well want to spray lots of water around for cleaning purposes, so I'd prefer not to have to worry.

I saw a reference to an IP44-rated lightswitch that looked normal, made by Clipsal, but I cannot find any more details.

Cheers,

Pete

Reply to
Pete Verdon

Yep, that's almost exactly what I have in mind, except for using a flow switch on the shower rather than a humidity sensor. Fan would be on while showering, and for a timer-duration thereafter.

In this case I don't think it's likely to get water on it, and in any case its design would discourage entry even though it hasn't actually been certified.

Probably, from a practical purpose, but I really don't like the things. One of them (for the light) is just about acceptable since it's so common, but multiple dangling strings (a mate's bathroom has three) drive me nuts.

I'm not worried about maintainability, more whether the inside of the boxing-in counts as part of the bathroom, since this alternative approach would mean it contains mains equipment (and the connections to the back of the button aren't IP-sealed). I know that the space under a bath is non-zoned only if there is a panel whose removal requires tools

- to have my studwork treated the same way I want access to be more difficult, not less :-)

Cheers,

Pete

Reply to
Pete Verdon

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